Using Level 2 Products to anticipate convective development in the south Pacific ocean
The animation above, created at the CSPP Geosphere site (direct link to the animation), shows showers dissipating over and south of the Samoan island chain shortly after sunset, and then redeveloping to the north of the island chain. The redevelopment in the RGB imagery followed the usual color change associated with developing convection: faint pink/red colors that became deeper and deeper red as clouds grew. Note that the RGB also has characteristic color — blue — that suggests clear skies. This means that clear-sky Level 2 products from GOES-18 such as Total Precipitable Water (TPW) and Derived Stability Indices might give useful information to help a forecaster anticipate the redevelopment of convection. The animations below show those TPW and Lifted Index overlain on top of GOES-18 “Clean Window” Band 13 infrared (10.3) imagery, from 0600 – 1000 UTC; the animations end before the developing convection generated clouds to mask the view. Note also that the Default AWIPS enhancements for TPW and Lifted Index have been altered, as noted in the caption.
The convection at the beginning of the animation was aligned along the southern edge of abundant total precipitable water, and it dissipated as it moved to slightly more stable air, that is, air with slightly less negative Lifted Indices (brighter yellow in the animation). There is greater instability to the north — and that’s where convection subsequently developed as noted in the Night MIcrophysics RGB animation.
Make sure you look at Level 2 Products such as TPW and Lifted Index (or CAPE, or K Index, or Total Totals Index) when skies are clear to get a better idea of gradients in regions that are void of data other than satellite information.